1. Field of the Invention
The present invention relates in general to methods and apparatus for analyzing certain characteristics of conductive items, and more particularly to matrix analyzers for identifying the characteristics of an ink droplet jetted from an inkjet printer.
2. Description of the Related Art
The operation of the printhead of an inkjet printer involves the jetting of a droplet of ink onto a print medium, such as paper. The printhead is constructed with an array of nozzles through which the ink is jetted into very small droplets. In order to produce an image on the print medium, such as words, letters or symbols, the size and location of the ink droplets is critical and must be within predetermined specifications. Thus, when manufacturing inkjet printheads, it is necessary to conduct tests thereon in order to assure that every nozzle is not only operational, but also to verify that the size and location of the droplet is within specified limits. During the use of printheads in inkjet printers, it becomes necessary to periodically conduct tests in order to verify the proper operation of the nozzles of the printhead. There are many other areas in other technologies where the size and/or location of a conductive item is required to be determined with specificity.
The analysis of the size of an ink droplet jetted from the printhead of an inkjet printer, and placement thereof in relation to the droplets of other printhead nozzles, has typically been performed using visual techniques. Owing to the fact that printhead designs have advanced to the point where the ink droplet is barely visible to the naked eye, the visual analysis has been made much more difficult. The visual analysis technique typically requires the determination of a light to dark threshold of the boundaries of the ink droplet. A printhead is tested by printing a test page. The characters of the test page are magnified using a high resolution camera. The magnified images are then visually inspected to verify whether the printhead nozzles have operated properly. With this technique, it is difficult to distinguish the boundary of the color yellow with the white test paper. When different colored inks are employed, the imaging device requires special control and special handling of the digital representation of the image to determine the size and location of the ink droplet. The size and location characteristics of the droplet jetted from a printhead is important to assure the quality of the printhead. However, the existence of any smaller satellite droplets adjacent to the primary ink droplet is also critical to the determination of the operability of the printhead. It can be appreciated that when using an invisible or transparent liquid, the visual analysis thereof is made much more difficult.
From the foregoing, it can be seen that a need exists for a method and corresponding apparatus for detecting size/location characteristics of an ink droplet by electrical means. A further need exists for a technique to detect the size and location characteristics of an ink droplet that is transparent. Yet another need exists for a technique to determine the size and location characteristics of an ink droplet with an accuracy and speed much better than currently available with visual techniques. A further need exists for a semiconductor device that can detect the size and location characteristics of an ink droplet with very high accuracy, and at a low cost.